A) Most likely you've
seen stereo pictures somewhere at some time. They are two pictures taken of
the same scene from two slightly different angles. View the pictures so that
each eye sees a different picture and voila: apparent three dimensionality.

Q) What's a JPS
file?

A) I downloaded the
free 3D driver from Nvidea. This driver
allows you to play hundreds of 3D games in stereo. Packaged with the driver
is a viewer for JPS files. If I'd heard of JPS files before, I hadn't really
figured out what they were, so I went searching for information on the Internet.
Here's what I found:

A JPS file is really
just a JPG file with a different extension. It contains two identically sized
pictures arranged side by side. If you view this picture in a JPG viewer,
you'll see the right eye view on the left and the left eye view on the right.
This is commonly referred to as "cross-eyed view". That's because
to "free view" the stereo picture you need to cross your eyes.

Q) Where can I
find JPS files?

A) Go fish! Of course
I mean on the Internet. There are actually a lot of JPS pictures posted on
the web. There are also newsgroups such as alt.binaries.pictures.stereo
which have pictures. Here are links to a few JPS files I've made (beware,
they are pretty big):

Q) How do I make
JPS files?

A) If you already
have stereo pair pictures, you're almost there. If you don't, there are several
good tutorials out on the Internet on how to produce them photographically
or in a program that you can use to render 3D drawings.

Once you have your
stereo pair, you need to combine the two images into a single JPG file. It's
best if you keep the files in some lossless format like TIFF, PNG or BMP while
you are working on them and convert them to JPG at the very end.

Open your bitmap editor,
almost any will do. Create a new drawing that is as tall as your pictures
and twice as wide. Import the right eye image and paste it on the left side.
Paste your left eye image on the right side. Save the resultant image. Rename
it with a JPS extension and you have it. Open your file up in a JPS viewer
and admire your handiwork.

Q) What's DepthCharge?

A) DepthCharge is
a free plug-in for Netscape and Internet Explorer. It allows you to view JPS
files in web pages. I find it does a great job and it allows you to display
pictures in a large number of different formats.

Q) What's wrong
with DepthCharge

A) The only problem
is that VRex, the nice folks who made DepthCharge,
also make a program called DepthCharge Developer Studio. In the past DepthCharge
worked on all JPS files but now only works with those created by DepthCharge
Developer Studio (I make this assumption based on pages I find that say they
work with DepthCharge, but that don't work with the version of DepthCharge
that I have.) I suppose that boosts sales. Maybe. However, I already have
a number of graphics editors and don't feel like dropping $79 for another
one that I doubt has any features I can't get by without.

Q) Why don't my
JPS files work with DepthCharge?

A) I decided to see
if there were any significant improvements made to the JPG standard file format
by the DepthCharge Developer Studio. I downloaded a JPS file from the Internet
that actually works with DepthCharge and compared it to one I'd made (that
didn't work with DepthCharge). Using a file from wotsit.org
as a guide to how a JPG file is formatted inside, I checked out the differences
I found and determined that the only difference was an extra little chunk
that didn't do anything useful (unless you consider DepthCharge not working
with your files useful.)

Q) Is there anyway
to make my homemade JPS files work with DepthCharge?

After a few minutes
of thought I decided that it would be pretty trivial to patch a JPS file to
include the goofy little VRex piece. If you are interested, here's
the C source code. I'm sorry, the only platform I compiled it for was
the DOS command line. If you are using another operating system, it should
be generic enough to work anywhere.

Here
is the program I wrote as a PC executable (if you have problems downloading
the .exe file, here's a zip file of the same thing.)
There are two ways to use it. The simplest is to put it on your desktop and
drag and drop files you want "fixed" onto it. It shouldn't hurt
other file types but I'm certainly not warranting it, so don't do anything
stupid (like drop important files on it.) The second way to use it is from
the command line:

jpsjps file1.jps file2.jps

It should be able
to handle as many file names as you care to pass to it.

If you don't understand
what any of the stuff above means, please find someone more computer literate
to help you.

NOTES:

Since I wrote this,
I've gotten feedback that the executable crashes under Windows 2000. I don't
currently have a Windows 2000 machine so I can't verify or repair it. I've
tested it, and it works fine, under Windows 98 and Windows NT 4.0. As soon
as I can, I'll get access to a Windows 2000 machine and try to replicate and
repair the reported problem. If you have tried jpsjps.exe I'd be very interested
in hearing about your experience with it, please write. Thanks, Tim
Kemp. (2 July 2006)